50 Fun Facts About High School Biology

Which farm animal was Dolly, the first mammal cloned from an adult body cell, born in Scotland in 1996?

Dolly was a Finn-Dorset sheep, cloned at the Roslin Institute from a single mammary gland cell. Her preserved body is on display at the National Museum of Scotland in Edinburgh.

Which organelle, normally inherited only from the mother, supplies most of a cell's chemical energy?

The mitochondrion carries its own small genome, similar to a bacterium's. In mammals the father's copies, delivered by the sperm, are usually destroyed by the egg cell after fertilization.

Which chemist led the X-ray diffraction work at King's College London that produced Photo 51 of DNA?

Rosalind Franklin's team produced Photo 51 in 1952, an image taken by her student Raymond Gosling. Its diffraction pattern revealed the helical shape of DNA.

Which DNA base pairs with adenine in the double helix but is normally missing from RNA?

Thymine binds to adenine in DNA, while RNA uses uracil in its place. Chemically the two are close cousins: thymine is uracil with one extra methyl group attached.

Which Augustinian friar established the basic rules of heredity by cross-breeding pea plants in the 1850s and 1860s?

Gregor Mendel tracked seven traits of his pea plants, among them seed shape and flower color. Recognition as the founder of genetics came only after his death.

Which naturalist's five-year voyage on HMS Beagle led to the book On the Origin of Species?

Charles Darwin sailed on the Beagle from 1831 to 1836. A keen taster of exotic animals, he ate puma, iguana and armadillo along the way, and by mistake a rhea he had meant to study.

Which English scientist coined the biological term cell in Micrographia, a 1665 book of microscope observations?

Robert Hooke coined the term for the tiny walled pores he saw in a thin slice of cork, which he compared to a honeycomb.

Which enzyme in human saliva starts digestion by splitting starch into simpler sugars?

Amylase is why starchy foods such as rice and potatoes can turn sweet as they are chewed. It is already converting some of their starch into sugar before they are swallowed.

Which inherited blood disorder did Queen Victoria pass to the royal families of Spain, Germany and Russia?

Hemophilia reached three royal houses through two of Victoria's daughters, Alice and Beatrice. Tests on the remains of Russia's Romanovs suggest it was the rarer form, type B.

Which genetic condition is caused by the presence of all or part of a third copy of chromosome 21?

Down syndrome is named after John Langdon Down, the English physician who described it in the 1860s. Its genetic cause was not discovered until 1959.

Which subatomic particles do two atoms share in pairs to form a covalent bond?

Electrons shared in pairs hold atoms together, an idea the chemist Gilbert Lewis proposed in 1916. Carbon can form four such bonds at once, enough to build the skeleton of every organic molecule.

Which term describes atoms of one element with different numbers of neutrons, the basis of radiometric dating?

Isotopes of an element share a proton count but differ in mass. Radiometric dating compares a radioactive one with the decay products it turns into at a known, constant rate.

Which weak attraction between neighboring water molecules gives water its high surface tension and boiling point?

Hydrogen bonds make water molecules cling together so tightly that trees can pull it more than 100 m up their trunks.

Which class of biological molecules includes fats, waxes and sterols and does not dissolve readily in water?

Lipids are hydrophobic, and that is what makes them useful. Those with one water-loving end line up in sheets, forming the thin membranes around cells.

Which branched carbohydrate do humans store in the liver and skeletal muscles as an energy reserve?

Glycogen is the animal counterpart of plant starch. Liver stores keep blood sugar steady between meals, while muscle stores are mostly burned on the spot by the muscle that holds them.

Which element do bacteria living in the root nodules of legumes capture from the air and turn into ammonia?

Nitrogen gas from the air becomes ammonia inside the nodules, and the plant builds it into amino acids. It is why legumes such as clover, soybeans and peanuts need less fertilizer.

Which particle, found in every living cell, builds proteins by reading the code in messenger RNA?

A ribosome is two subunits locked around a strand of messenger RNA. Bacterial ones differ enough from ours that some antibiotics can jam them while leaving human cells unharmed.

Which process moves water through a selectively permeable membrane toward the side with more dissolved solute?

Osmosis is the main agent of support in many plants. Water flowing into their cells presses against the cell walls, and when that pressure is lost the plant wilts.

Which group of organisms, made up of bacteria and archaea, has cells with no membrane-bound nucleus?

Prokaryotes take their name from Greek words for 'before' and 'kernel', a nod to cells that came before the nucleus. They reproduce asexually, usually by splitting in two.

Which molecule, often called the energy currency of the cell, drives muscle contraction and nerve impulses?

ATP is spent and rebuilt so quickly that a typical adult gets through roughly their own body weight of it over the course of a day.

Which event in prophase I of meiosis swaps DNA segments between paired chromosomes, shuffling a parent's genes?

Crossing over is why siblings differ: each chromosome a parent passes on is a fresh patchwork of the two that parent inherited. Thomas Hunt Morgan built the theory on what Frans Janssens saw in 1909.

Which term describes a cell, such as a human sperm or egg, that carries only one set of chromosomes?

Haploid cells are made when meiosis splits the 46-chromosome human set in half. Two of them then fuse at fertilization, restoring the full count.

Which single cell forms when a sperm fertilizes an egg, combining two sets of chromosomes?

Zygote comes from a Greek word meaning 'joined' or 'yoked'. In humans it makes its first division, into two cells, about 30 hours after fertilization.

Which meiosis error, a failure of chromosomes to separate, leaves cells with an abnormal chromosome number?

Nondisjunction in humans most often traces to the egg rather than the sperm, and the risk climbs with the mother's age. The cells that result carry a chromosome too many or too few.

Which stage of mitosis lines the chromosomes up along the cell's equator before they are pulled apart?

Metaphase holds every chromosome in a tug-of-war between fibers pulling from opposite poles. A checkpoint lets division continue only once each one is attached and evenly balanced.

In which part of the cell cycle, before mitosis begins, does a cell grow and copy its DNA?

Interphase is where a cell spends most of its life. Typical cells of adult mammals stay in it for about 24 hours, at least 90% of the time a full round of division takes.

Which constricted region of a chromosome links the two sister chromatids together during cell division?

The centromere divides each chromosome into a short arm, labeled p, and a long arm, labeled q. The p is said to stand for the French word petit, meaning small.

Which pair of scientists published the double helix model of DNA in the journal Nature in 1953?

Watson and Crick fitted the model into a paper barely a page long, printed on pages 737 and 738 of the journal. The two shared a Nobel Prize for it with Maurice Wilkins in 1962.

Which enzyme separates the two strands of DNA at the replication fork so that each can be copied?

Helicase works like a motor, burning cellular fuel to push the two strands apart. Some versions do the job as ring-shaped clusters of six units.

Which three-base unit of messenger RNA specifies a single amino acid in a growing protein?

A codon is one of 64 possible three-letter combinations, though cells use only 20 standard amino acids. Three of the 64 mean stop, and carry the names amber, ochre and opal.

Which process, carried out by RNA polymerase, copies the DNA sequence of a gene into messenger RNA?

Transcription produces only a rough draft at first. In human cells, stretches called introns are then cut out of the RNA before the finished message is ready to be read.

Which word describes DNA replication, because each new double helix keeps one strand from the original molecule?

Semiconservative copying was confirmed by the Meselson–Stahl experiment of 1958. Keeping one old strand also gives the cell a template for repairing mistakes in the new one.

Which short stretches of newly made DNA are later joined together to build the lagging strand during replication?

Okazaki fragments are named for Reiji and Tsuneko Okazaki, the husband-and-wife team who discovered them in the 1960s. The enzyme DNA ligase stitches them into one continuous strand.

Which protective caps of repeated DNA at the ends of chromosomes get shorter each time a body cell divides?

Telomeres stop repair systems from mistaking a chromosome's tip for broken DNA. The discovery of how they protect chromosomes won the 2009 Nobel Prize in Physiology or Medicine.

Which inherited disorder stems from a single-base mutation yet gives carriers some protection against severe malaria?

Sickle cell disease needs two copies of the altered gene. People with just one copy usually have no symptoms, and where malaria is common that single copy is an advantage.

Which diagram do biology students draw to predict the genotypes of offspring from a genetic cross?

The Punnett square is named after Reginald Punnett, the British geneticist who devised it in 1905. Capital letters in its boxes stand for dominant alleles and lower-case letters for the others.

Which term covers an organism's observable traits, such as height or blood group, as opposed to its genes?

Phenotype comes from Greek words meaning 'to show' and 'type'. It is shaped by environment as well as genes, a distinction Wilhelm Johannsen drew in 1911.

Which word describes an allele, like the one for cystic fibrosis, whose effect is masked by a dominant partner?

Recessive alleles can pass unnoticed through carriers for generations. Cystic fibrosis appears only when a child inherits a faulty copy from both parents.

Which inheritance pattern explains blood type AB, in which the A and B alleles are both fully expressed?

Codominance means neither allele masks the other, so a type A parent and a type B parent can have an AB child. In incomplete dominance the result is an in-between blend instead.

Which insect did Thomas Hunt Morgan breed at Columbia University to show that genes are carried on chromosomes?

The fruit fly made Morgan's lab at Columbia famous as the Fly Room and earned him the 1933 Nobel Prize in Physiology or Medicine. It went on to become a major model organism in genetics.

Which gas do plants release as a by-product when they split water molecules during photosynthesis?

Oxygen is simply the leftover of splitting water. Cyanobacteria releasing it this way transformed Earth's atmosphere more than two billion years ago.

Which pigment in plant leaves absorbs mostly red and blue light, leaving the green to be reflected?

Chlorophyll is built around a magnesium atom, much as the heme in blood is built around iron. Its name comes from Greek words for pale green and leaf.

Which series of light-independent reactions turns carbon dioxide into sugar in the stroma of a chloroplast?

The Calvin cycle was discovered in 1950 by Melvin Calvin, James Bassham and Andrew Benson, who tracked radioactive carbon-14 through its steps. Calvin won the 1961 Nobel Prize in Chemistry.

Which substance, also found in yogurt and sauerkraut, do muscle cells make during anaerobic fermentation?

Lactic acid was long blamed for the muscle soreness felt days after hard exercise. That theory has been largely rejected, since levels return to normal within about an hour.

Which process explains why dark peppered moths replaced pale ones in soot-covered industrial England?

Natural selection later ran the other way. Once clean air laws cut the pollution, the pale form of the moth became the common one again.

Which Pacific island group is home to finches whose varied beaks became a textbook case of adaptive radiation?

The Galápagos Islands, a province of Ecuador, are the only home of all but one of the roughly 18 finch species in the group. The exception lives on Cocos Island, off Costa Rica.

Which model in population genetics, named for a mathematician and a physician, predicts unchanging allele frequencies?

Hardy–Weinberg is named for G. H. Hardy, a British pure mathematician, and Wilhelm Weinberg, a German physician, who each worked it out in 1908. It holds only while no evolutionary force is acting.

Which kind of symbiosis, seen when bees feed on nectar and pollinate flowers, benefits both species involved?

Mutualism also describes the bacteria of the human gut, which evolved alongside our species. The arrangement is beneficial both to the human host and to the microbes.

Which kind of species, like the sea otter in a kelp forest, holds a whole ecosystem together?

Keystone species are named after the top stone of an arch, which bears the least pressure yet brings the arch down if removed. Without otters, sea urchins graze kelp forests away.

Which American biologist argued in 1967 that chloroplasts and other organelles were once free-living bacteria?

Lynn Margulis saw her landmark paper rejected by about fifteen journals before it appeared. The theory was largely ignored for another decade, then confirmed by genetic evidence.